endfunction
-% init function
-% load function
-% default est on, but way to optionally disable
-
#{
Frame has Ns-1 data symbols between pilots, e.g. for Ns=3:
rand('seed',1);
states.pilots = 1 - 2*(rand(1,Nc+2) > 0.5);
+
+ w = (0:Nc+1)*2*pi*Rs/states.Fs;
+ W = zeros(Nc+2,states.M);
+ for c=1:Nc+2
+ W(c,:) = exp(j*w(c)*(0:states.M-1));
+ end
+ states.w = w;
+ states.W = W;
+
+endfunction
+
+
+% ---------------------------
+% Modulates one frame of bits
+% ---------------------------
+
+function tx = ofdm_mod(states, tx_bits)
+ ofdm_load_const;
+
+ assert(length(tx_bits) == Nbitsperframe);
+
+ % map to symbols in linear array
+
+ if bps == 1
+ tx_sym_lin = 2*tx_bits - 1;
+ end
+ if bps == 2
+ for s=1:Nbitsperframe/bps
+ tx_sym_lin(s) = qpsk_mod(tx_bits(2*(s-1)+1:2*s));
+ end
+ end
+
+ % place symbols in multi-carrier frame with pilots and boundary carriers
+
+ tx_sym = []; s = 1;
+ aframe = zeros(Ns,Nc+2);
+ aframe(1,:) = pilots;
+ for r=1:Nrowsperframe
+ arowofsymbols = tx_sym_lin(s:s+Nc-1);
+ s += Nc;
+ aframe(r+1,2:Nc+1) = arowofsymbols;
+ end
+ tx_sym = [tx_sym; aframe];
+
+ % OFDM upconvert symbol by symbol so we can add CP
+
+ tx = [];
+ for r=1:Ns
+ asymbol = tx_sym(r,:) * W/M;
+ asymbol_cp = [asymbol(M-Ncp+1:M) asymbol];
+ tx = [tx asymbol_cp];
+ end
endfunction
phase_est_en = sim_in.phase_est_en;
if verbose
- printf("Rs:.........: %4.2f\n", Rs);
- printf("M:..........: %d\n", M);
+ printf("Rs:..........: %4.2f\n", Rs);
+ printf("M:...........: %d\n", M);
+ printf("Ncp:.........: %d\n", Ncp);
printf("bps:.........: %d\n", bps);
printf("Nbitsperframe: %d\n", Nbitsperframe);
printf("Nrowsperframe: %d\n", Nrowsperframe);
+ printf("Nsamperframe.: %d\n", Nsamperframe);
end
% Important to define run time in seconds so HF model will evolve the same way
% init timing est states
- tstates.Nsamperframe = Nsamperframe; tstates.M = M; tstates.Ncp = Ncp;
- tstates.verbose = 0; tstates.Fs = Fs;
delta_t = [];
window_width = 11; % search window_width/2 from current timing instant
EbNo = bps * (10 .^ (EbNodB(nn)/10));
variance = 1/(M*EbNo/2);
- % generate tx bits
-
- tx_bits = rand(1,Nbits) > 0.5;
-
- % map to symbols in linear array
+ Nsam = Nrp*(M+Ncp);
- if bps == 1
- tx_sym_lin = 2*tx_bits - 1;
- end
- if bps == 2
- for s=1:Nbits/bps
- tx_sym_lin(s) = qpsk_mod(tx_bits(2*(s-1)+1:2*s));
- end
- end
+ % generate tx bits and run OFDM modulator
- % place symbols in multi-carrier frame with pilots and boundary carriers
+ tx_bits = rand(1,Nbits) > 0.5;
- tx_sym = []; s = 1;
+ tx = [];
for f=1:Nframes
- aframe = zeros(Nrowsperframe,Nc+2);
- aframe(1,:) = pilots;
- for r=1:Nrowsperframe
- arowofsymbols = tx_sym_lin(s:s+Nc-1);
- s += Nc;
- aframe(r+1,2:Nc+1) = arowofsymbols;
- end
- tx_sym = [tx_sym; aframe];
- end
- tx_sym = [tx_sym; pilots]; % final row of pilots
- [nr nc] = size(tx_sym);
- assert(nr == Nrp);
-
- % OFDM up conversion and upsampling to rate Fs ---------------------
-
- w = (0:Nc+1)*2*pi*Rs/Fs;
- W = zeros(Nc+2,M);
- for c=1:Nc+2
- W(c,:) = exp(j*w(c)*(0:M-1));
+ tx = [tx ofdm_mod(states, tx_bits((f-1)*Nbitsperframe+1:f*Nbitsperframe))];
end
- Nsam = Nrp*(M+Ncp);
- tx = [];
-
- % OFDM upconvert symbol by symbol so we can add CP
+ % add extra row of pilots at end, to allow one frame simulations,
+ % useful for development
- for r=1:Nrp
- asymbol = tx_sym(r,:) * W/M;
- asymbol_cp = [asymbol(M-Ncp+1:M) asymbol];
- tx = [tx asymbol_cp];
- end
+ st = Nsamperframe*(Nframes-1)+1; en = st+Ncp+M-1;
+ tx = [tx tx(st:en)];
assert(length(tx) == Nsam);
% OFDM symbol of pilots is used for coarse timing and freq during acquisition, and fine timing
+ % TODO: put this in init code
rate_fs_pilot_samples = tx(1:M+Ncp);
% pilot based phase est, we use known tx symbols as pilots ----------
rx_sym = zeros(Nrp, Nc+2);
+ rx_sym1 = zeros(1+Ns+1+1, Nc+2);
+
phase_est_pilot_log = 10*ones(Nrp,Nc+2);
phase_est_stripped_log = 10*ones(Nrp,Nc+2);
phase_est_log = 10*ones(Nrp,Nc+2);
foff_est_gain = 0.1;
Nerrs_log = [];
+ % place samples in rx_buf, which is 3 and a bit frame long
+
+#{
+ [ ] OK have rxbuf doing ofdm d/c using fixed time refs and rxbuf update
+ [ ] now need rx_sym to work based on fixed time refs
+ + but then need to make that work with moving time ref output for now
+ + so transition works after phase correction
+#}
+
+ nin = Nsamperframe;
+
+ % Maintain buffer of 3 frames plus one pilot:
+ %
+ % P DDD P DDD P DDD P
+
+ Nrxbuf = 3*Nsamperframe+M+Ncp;
+ rxbuf = zeros(1, Nrxbuf);
+ prx = 1;
+
+ % for this simulation we "prime" buffer to allow one frame runs during development
+
+ rxbuf(2*Nsamperframe+1:Nrxbuf) = rx(prx:Nsamperframe+M+Ncp);
+ prx += Nsamperframe+M+Ncp;
+
for r=1:Ns:Nrp-Ns
+ % insert samples at end of buffer, set to zero if no samples
+ % available to disable phase estimation on future pilots at end
+ % of simulation
+
+ rxbuf(1:Nrxbuf-Nsamperframe) = rxbuf(Nsamperframe+1:Nrxbuf);
+ rxbuf(Nrxbuf-Nsamperframe+1:Nrxbuf) = zeros(1,Nsamperframe);
+ lnew = min(Nsam-prx,Nsamperframe);
+ printf("prx: %d lnew: %d Nrxbuf: %d\n", prx, lnew, Nrxbuf);
+ if lnew
+ rxbuf(Nrxbuf-Nsamperframe+1:Nrxbuf-Nsamperframe+lnew) = rx(prx:prx+lnew-1);
+ end
+ prx += Nsamperframe;
+
% printf("symbol r: %d\n", r);
woff_est = 2*pi*foff_est_hz/Fs;
% previous pilot
- if r >= Ns+1
+ %if r >= Ns+1
rr = r-Ns;
+ rrr = rr - r + 1;
st = (rr-1)*(M+Ncp) + 1 + sample_point; en = st + M - 1;
+ st1 = Nsamperframe + (rrr-1)*(M+Ncp) + 1 + sample_point; en1 = st1 + M - 1;
+ printf(" r: %d rr: %d rrr: %d st: %d st1: %d\n", r, rr, rrr, st, st1);
for c=1:Nc+2
- acarrier = rx(st:en) .* exp(-j*woff_est*(st:en)) .* conj(W(c,:));
- rx_sym(rr,c) = sum(acarrier);
+ acarrier = rxbuf(st1:en1) .* exp(-j*woff_est*(st:en)) .* conj(W(c,:));
+ %rx_sym(rr,c) = sum(acarrier);
+ rx_sym1(1,c) = sum(acarrier);
end
%printf(" rr: %d st: %d en: %d\n", rr, st, en);
- end
+ %end
% pilot - this frame - pilot
+ printf("-------------frame r: %d\n", r);
+ rrrr = 2;
for rr=r:r+Ns
+ rrr = rr - r + 1;
st = (rr-1)*(M+Ncp) + 1 + sample_point; en = st + M - 1;
+ st1 = Nsamperframe + (rrr-1)*(M+Ncp) + 1 + sample_point; en1 = st1 + M - 1;
+ printf(" r: %d rr: %d rrr: %d st: %d st1: %d\n", r, rr, rrr, st, st1);
+ rx(st:st+3)
+ rxbuf(st1:st1+3)
for c=1:Nc+2
- acarrier = rx(st:en) .* exp(-j*woff_est*(st:en)) .* conj(W(c,:));
- rx_sym(rr,c) = sum(acarrier);
+ acarrier = rxbuf(st1:en1) .* exp(-j*woff_est*(st1:en1)) .* conj(W(c,:));
+ %rx_sym(rr,c) = sum(acarrier);
+ rx_sym1(rrrr,c) = sum(acarrier);
end
+ rrrr++;
%printf(" rr: %d st: %d en: %d\n", rr, st, en);
end
% next pilot
- if r <= Nrp - 2*Ns
+ %if r <= Nrp - 2*Ns
rr = r+2*Ns;
+ rrr = rr - r + 1;
st = (rr-1)*(M+Ncp) + 1 + sample_point; en = st + M - 1;
+ st1 = Nsamperframe + (rrr-1)*(M+Ncp) + 1 + sample_point; en1 = st1 + M - 1;
for c=1:Nc+2
- acarrier = rx(st:en) .* exp(-j*woff_est*(st:en)) .* conj(W(c,:));
- rx_sym(rr,c) = sum(acarrier);
+ acarrier = rxbuf(st1:en1) .* exp(-j*woff_est*(st:en)) .* conj(W(c,:));
+ %rx_sym(rr,c) = sum(acarrier);
+ rx_sym1(rrrr,c) = sum(acarrier);
end
% printf(" rr: %d st: %d en: %d\n", rr, st, en);
- end
+ %end
+ rrrr
+ assert(rrrr == (Ns+3));
% est freq err based on all carriers
% PPP
cr = c-1:c+1;
- aphase_est_pilot_rect = sum(rx_sym(r,cr)*tx_sym(r,cr)') + sum(rx_sym(r+Ns,cr)*tx_sym(r+Ns,cr)');
+ %aphase_est_pilot_rect = sum(rx_sym(r,cr)*pilots(cr)') + sum(rx_sym(r+Ns,cr)*pilots(cr)');
+ aphase_est_pilot_rect = sum(rx_sym1(2,cr)*pilots(cr)') + sum(rx_sym1(2+Ns,cr)*pilots(cr)');
% use next step of pilots in past and future
- if r >= Ns+1
- aphase_est_pilot_rect += sum(rx_sym(r-Ns,cr)*tx_sym(r-Ns,cr)');
- end
- if r <= Nrp - 2*Ns
- aphase_est_pilot_rect += sum(rx_sym(r+2*Ns,cr)*tx_sym(r+2*Ns,cr)');
- end
+ %if r >= Ns+1
+ %aphase_est_pilot_rect += sum(rx_sym(r-Ns,cr)*pilots(cr)');
+ aphase_est_pilot_rect += sum(rx_sym1(1,cr)*pilots(cr)');
+ %end
+ %if r <= Nrp - 2*Ns
+ %aphase_est_pilot_rect += sum(rx_sym(r+2*Ns,cr)*pilots(cr)');
+ aphase_est_pilot_rect += sum(rx_sym1(2+Ns+1,cr)*pilots(cr)');
+ %end
% correct phase offset using phase estimate
+ rrrr = 3;
for rr=r+1:r+Ns-1
aphase_est_pilot = angle(aphase_est_pilot_rect);
phase_est_pilot_log(rr,c) = aphase_est_pilot;
if phase_est_en
+ % rx_corr(rr,c) = rx_sym(rr,c) * exp(-j*aphase_est_pilot);
rx_corr(rr,c) = rx_sym(rr,c) * exp(-j*aphase_est_pilot);
+ rx_corr(rr,c) = rx_sym1(rrrr,c) * exp(-j*aphase_est_pilot);
else
- rx_corr(rr,c) = rx_sym(rr,c);
+ %rx_corr(rr,c) = rx_sym(rr,c);
+ rx_corr(rr,c) = rx_sym1(rrrr,c);
end
+ rrrr++;
end
end % c=2:Nc+1
+
end % r=1:Ns:Nrp-Ns
sim_in.Tcp = 0.002;
sim_in.Rs = 1/Ts; sim_in.bps = 2; sim_in.Nc = 16; sim_in.Ns = 8;
- %sim_in.Nsec = 1*(sim_in.Ns+1)/sim_in.Rs; % one frame
- sim_in.Nsec = 10;
+ sim_in.Nsec = 5*(sim_in.Ns+1)/sim_in.Rs; % one frame
+ %sim_in.Nsec = 30;
- sim_in.EbNodB = 6;
+ sim_in.EbNodB = 100;
sim_in.verbose = 1;
- sim_in.hf_en = 1;
+ sim_in.hf_en = 0;
sim_in.foff_hz = 0;
- sim_in.timing_en = 1;
+ sim_in.timing_en = 0;
sim_in.sample_clock_offset_ppm = 0;
- sim_in.foff_est_en = 1;
+ sim_in.foff_est_en = 0;
sim_in.phase_est_en = 1;
run_sim(sim_in);
projects / freetel-svn-tracking.git / commitdiff